Dipeptidyl Peptidase IV from Human Serum: Purification, Characterization, and N-Terminal Amino Acid Sequence

Abstract

Dipeptidyl peptidase IV (DPP IV) in normal human serum was purified 14,400-fold with a 25% yield to homogeneity. The molecular weight of the purified enzyme was approximately 110,000 on SDS-PAGE, almost the same as that of human kidney membrane-bound DPP IV. No difference was found between the two enzymes enzymologically and immunologically, either in substrate specificity, susceptibility to inhibitors, or cross-reactivity with an anti-rat kidney DPP IV antibody, or in their ability to bind adenosine deaminase. However, the N-terminal amino acid sequence of serum DPP IV lacked the transmembrane domain of the membrane-bound enzyme and started at the 39th position, serine, from the N-terminus predicted from the cDNA nucleotide sequence. These results suggest that membrane-bound DPP IV loses its transmembrane domain upon release into the serum, and that its structure on the plasma membrane is not required for its binding to adenosine deaminase.

Monitoring of the effects of transfection with baculovirus on Sf9 cell line and expression of human dipeptidyl peptidase IV

“…hDPPIV regulates various physiological processes including immune system, endocrine functions, central nervous system, gastrointestinal system, inflammation, rheumatoid arthritis and cell adhesion. The enzyme removes dipeptides from N-terminus of regulatory peptides such as chemokines, neuropeptides and peptide hormones (Reichelt et al 1981;Shattock et al 1990; Urade et al 2006;Iwaki-Egawa et al 1998;Mentlein 1999;Brudnak 2001;Brudnak et al 2002;Langford 2003;Lambeir et al 2002;Reichelt and Knivsberg 2003;Aertgeerts et al 2004;Reinhold et al 2009). …”

Novel dipeptidyl peptidase IV resistant analogues of glucagon-like peptide-1(7-36)amide have preserved biological activities in vitro conferring improved glucose-lowering action in vivo

“…However, a major limiting factor in such a use for GLP-1 is its susceptibility to degradation and inactivation in vivo by dipeptidyl peptidase IV (DPP IV; EC.3·4·14·5) -a member of the prolyl oligopeptidase family of serine proteases (Barrett & Rawlings 1992). DPP IV is ubiquitously found in mammalian organs and tissues including serum (Iwaki-Egawa et al 1998) and cleaves peptides that contain penultimate proline, alanine or hydroxyproline residues (Mentlein 1999). In the case of GLP-1, DPP IV rapidly (t 1/2 2-3 min) cleaves the His 7 -Ala 8 dipeptide from the N-terminus generating GLP-1(9-36)amide (Mentlein et al 1993).…”

Dipeptidyl peptidase IV (CD26) activity in the hematopoietic system: differences between the membrane-anchored and the released enzyme activity

“…DPP-IV is a membrane-anchored enzyme with its catalytic site in the pericellular environment and it can also be cleaved and released from the cell membrane (18). The cysteine-rich region of DPP-IV contains fibronectin and collagen-binding sites, and the released enzyme can secondarily associate with the extracellular matrix, potentially generating gradients or focal microenvironments with specific enzyme activity (19).…”